California Keeps Its Energy Cool in Summer Scorcher

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California Keeps Its Energy Cool in Summer Scorcher

A natural gas turbine's exhaust duct is pictured at the Colusa Generating Station in Maxwell, California. Over the past 13 years, the state has added more than 15,000 megawatts of natural gas-fired electricity generation, which helped ensure supply when a heat wave hit last week.

Photograph by Ken James, Bloomberg/Getty Images

The stage was set for a California power crunch: A blistering heat wave was expected to blanket much of the state, and ocean breezes that normally cool sunbaked valleys and deserts overnight looked unlikely to waft far inland.

Power supplies, meanwhile, were worryingly tight, because low snowpacks had hobbled hydropower resources and California's two large nuclear plants—among the state's largest electricity generators—were shut down.

Yet when temperatures rose over a weeklong period to record highs throughout the Golden State—well above 110⁰F (43.3⁰C) in some places before the wave lifted July 5—the lights stayed on and air conditioners kept humming.

How did California do it? It wasn't wizardry, but mundane moves to bolster supply and curb demand—a combination of natural gas, renewable energy, and conservation—that made California more resilient than some forecasters anticipated when the heat rolled in.

"The flexibility and the adaptability of California's system really shone through," said Daniel Kammen, founding director of the Renewable and Appropriate Energy Laboratory at the University of California, Berkeley. "It absorbed major hits and came out running beautifully."

It's an episode that may have relevance far beyond California's borders. As the U.S. Department of Energy noted in a new report released Thursday, heat waves lasting days or weeks are expected to grow more frequent and more intense due to climate change, and may well become the dominant summertime condition in the United States before the end of the century. (See related story: "Climate Change Impact on Energy: Five Proposed Safeguards.") On Tuesday, New England's grid operator urged customers to conserve power, with near-record electricity demand forecast as a heat wave settled over the East Coast.

System operators are watching California to see if the state is indeed developing a viable formula for keeping power flowing to homes and offices in the heat-stressed new normal.

Dodging Rolling Blackouts

It wasn't that long ago—the summer of 2000—that California for a time became poster child for a bleak electricity future. The state had been in the vanguard of the electricity deregulation movement, but instead of offering more choice and efficiency, the new free market delivered costly rolling blackouts.

Only later did it become clear that market manipulation, most notoriously by the now-defunct energy trader Enron, had caused the shortages. "All of the rolling blackouts that occurred had nothing to do with insufficient supply," said Frank Wolak, economics professor at Stanford University. "They had to do with insufficient willingness of the guys that had the supply."

But this spring, California appeared to be facing genuine challenges. Leaks and equipment problems at the San Onofre Nuclear Generating Station, which once supplied enough power for 1.4 million homes, had forced the plant offline in early 2012. In early June, Southern California Edison announced it would close the plant for good. It was a blow for Southern California, which drives more than one-third of the state's electricity demand. "It's a rare, rare event where essentially we have insufficient total capacity to meet total demand," said Wolak, noting that this was not one of those events. "The more difficult challenge is you don't have enough in a given location."

The California Independent System Operator (CAISO), which manages the electric grid for most of California and parts of Nevada, noted that a number of improvements and upgrades to the state's transmission system were designed to keep power flowing despite the San Onofre outage. But California also was vulnerable because of its historic dependence on imported power from other states, said the North American Electric Reliability Corporation (NERC), the industry nonprofit responsible for ensuring stable power supply across the continent. Not only were hydropower levels low throughout the Pacific Northwest, but high-voltage transmission lines were stressed by demand. NERC singled out California as facing North America's worst operational challenges this year in its annual pre-summer assessment. (See related blog post: "Who Will Swelter This Summer?")

And then, just ahead of this summer's scorcher, Diablo Canyon nuclear plant, about 200 miles north of Los Angeles, which typically contributes about one-tenth of California's in-state power generation, had to shut down one of its two reactors due to a leak in a backup cooling system.

The approaching heat wave created the perfect storm for the electrical system. The state capital, Sacramento, braced for triple-digit temperatures and downtown Los Angeles was set to see the mercury rise close to its 98⁰F (36.7⁰C) record.

Cutting Demand

In an effort to tamp down electricity use, California utilities issued urgent calls for customers to adjust thermostats, use fans instead of power-hungry air conditioners, draw drapes, put off use of electrical appliances until evening or early morning, and take other steps to conserve. The state's Flex Alert program stresses simple, voluntary steps.

Programs through which businesses have opted to receive payments or reduced rates in exchange for dialing down energy use during extreme heat waves helped further dampen demand.

The utility Southern California Edison said its residential and business customers helped to lower peak demand by an estimated 300 megawatts over the course of the five-day heat wave. That's a savings equivalent to the momentary demand of about 200,000 California households.

"Without the thermal [natural gas] units supplying 10,000 megawatts more in the middle of the day than they did earlier in the day, the lights would have gone out," Wolak said. "This is what thermal units are good at doing: meeting demand. They are dispatchable."

It was the result of a concerted effort by the state, begun even before the 2000 electricity crisis, to bolster the state's electricity assets.

"Planners don't keep their jobs by being lucky," said Daniel Brooks, senior program manager for grid operations and planning at the Electric Power Research Institute (EPRI), a nonprofit organization funded by the U.S. electric power industry. "They keep their jobs by being thorough and having good margins."

Diablo Canyon's down reactor came back online near the end of the heat wave, but nuclear and hydropower hits notwithstanding, the state still had plenty of juice.

Renewables: Double-Edged

California's aggressive effort to ramp up renewable energy also came into play during the heat wave—but authorities initially were not certain if it would help or hurt efforts to keep the lights on.

Part of the challenge is that from moment to moment, electricity supplied to the grid must closely match the amount being consumed. If it doesn't, it can set grid frequency off kilter and have a destabilizing effect.

It didn't come down to that during this heat wave in California. Nor did the inherent ups and downs of power from the sun and wind impinge on reliability. Today, intermittent renewables just don't make up a fat enough slice of the pie to "get you into trouble," Wolak said. "If you're trying to put that up to maybe 33 percent and beyond, that's starting to look more dangerous. You're on the high wire without a net."

But during the recent heat wave, far from being a problem for the system, solar played an important role, argued Kammen, who is on the board of directors for an initiative of state utilities and regulators called California Energy Systems for the 21st Century. Solar averages only about one percent of California's total production today, an amount that "looks small," he said. "But the real story isn't what your average draw is, but what's the power draw at 4 p.m. on a hot day." That's the critical moment when a sliver of solar or wind can potentially make the difference between adequate supply and blackouts.

On July 1, demand on the CAISO system peaked shortly before 5 p.m. at nearly 45,000 megawatts. At that time, thermal plants—mostly natural gas—were providing the bulk of California's electricity, nearly 27,200 megawatts. Nuclear plants contributed about 1,100 megawatts; hydro chipped in another 4,800 megawatts or so. Renewables chipped in more than 4,400 megawatts—equivalent to the capacity of about two Hoover Dams. Not included in these statistics (which track only utility-scale capacity) are the solar panels that grace rooftops and provide intermittent power to tens of thousands of homes throughout the state.

A similar mix came together the following day, when system demand peaked earlier, around 3 p.m., at nearly 44,000 megawatts. Renewables, imported electricity, and thermal (primarily, natural gas) plants contributed the lion's share at the time, producing 4,800 megawatts, 6,300 megawatts, and 26,400 megawatts, respectively. Later in the day, around six o'clock, output from non-hydro renewables ramped up to exceed 6,000 megawatts, or nearly 15 percent of California's total electricity production at that hour.

At this point, renewables are a "large and important part of our power mix," said CAISO spokeswoman Stephanie McCorkle. But they are not considered a "peaking resource" that can be counted upon to meet the highest demand of the day. Even so, Kammen said, the Golden State is in a position where so much solar is coming onto the grid that power companies may soon need to reward customers for afternoon consumption in order to use the solar power generated at that hour. "That is a real paradigm shift," he said. When it comes to electricity, he added, "The new world is very strongly about how much we need at that peak moment, and that's when solar really shines."

It remains to be seen whether California's formula of conservation, natural gas, and renewable energy, will be sufficient to weather the difficult years ahead for the electric power system. Last year, the U.S. Department of Energy's Lawrence Berkeley National Laboratory concluded that elevated temperature would both increase California's electrical demand for cooling and reduce the efficiency of the state's existing generating stations; the researchers said that the state would need to provide an additional 38.5 percent peak generation capacity to meet these challenges while meeting per-capita energy demand at today's levels.

And as often has been the case, California is in the forefront of a nationwide trend. "Climate change and extreme weather risks facing the U.S. energy sector are varied, complex, and difficult to project in terms of probability, timing, and severity," said the U.S. Energy Department last Thursday in its report on climate impacts. "The magnitude of the challenge posed by climate change on an aging and already stressed U.S. energy system could outpace current adaptation efforts."